Post-fire soil recovery affected by soil depth and fire severity along a long-term chronosequence in a central European temperate forest

Abstract

Wildfires are currently becoming a global threat to forest ecosystems, affecting not only vegetation, but also key soil properties. Here we provide first insights into the long-term post-fire dynamics of soil properties as related to soil depth and fire severity in a Central European temperate forest. In this study, we investigated changes in soil physical, chemical and microbial properties in Scots pine-dominated forests along a unique 110-year-long post-fire chronosequence. We collected soil samples from the organic (O) and the surface mineral (0–5 cm, A) horizons affected by wildfire of either high or low severity. We show that the time needed to recover after the fire was longer for the physical and chemical properties (< 110 years) than for the microbial properties (< 45 years). Although the relative change in soil properties was larger in the A horizon than in the O horizon (60% vs. 46%), the absolute change determined the recovery time. The recovery time was therefore longer in the O horizon (< 110 years) than in the A horizon (< 9 years). Our data also indicate that the young sites showed significant effects of fire severity, with longer recovery times after high severity fires. Although the effects were only found in microbial properties, indicating their high sensitivity to fire, the differences clearly show that the O horizon is rather prone to fire severity, whereas the A horizon is relatively resilient.